Without knowing any info about your fitness, flexibility, riding style, etc- based on the info you've given a 525mm top tube should be the right "middle of the road" length for someone your size.
How much you can tolerate at the extremes is up to you, but all else being equal, I think getting a bike with a tt that's an inch too long would require you to make too many compromises (stem length, seat setback, etc).